Wire harnesses are used in complex systems to route bundles of wires between electrical components. For instance, in a typical vehicle the wires of an underhood wiring harness are strapped into separate wire bundles and routed through an opening in a firewall. The wire bundles are then connected to gauges, entertainment/navigation systems, power seats, or other electronic devices within a vehicle interior. A water-tight seal at the opening helps prevent leaks into the vehicle interior. One-piece sealing grommets in the form of hollow cylindrical inserts of rubber or a synthetic polymer material are typically used for this purpose. Sealing grommets may be radially flared and/or provided with an enlarged head so as to retain the grommet in an installed position with respect to the opening.
The electrical content in complex systems continues to increase. In some areas, a wiring harness must be routed through a restricted space, for example in an underhood compartment of a vehicle, between adjacent panels of an appliance, or through an exterior wall of a building. Bundled wires of a wiring harnesses can have a relatively large diameter, which in turn can make the wiring harness difficult to route between components within the restricted space. Moreover, once the wiring harness has been successfully routed through the panel opening, sufficient clearance must be maintained with respect to surrounding components, such as clutch, brake, and accelerator pedals of a vehicle interior. However, accurate and repeatable routing of relatively thick wire bundles of a wiring harness may be difficult to achieve using conventional cylindrical or flared sealing grommets.